The present disclosure relates to an image forming apparatus and more particularly to an image forming apparatus which includes a sheet storage cassette that is removable with respect to a cassette fitting portion in the main body of the image forming apparatus.
In an image forming apparatus such as a copying machine or a printer, a paper feed cassette (sheet storage cassette) is used in order to feed paper such as cut paper. In the paper feed cassette, a large number of sheets before printing are previously stocked in a sheet storage portion. The sheets stacked within the paper feed cassette are separated and supplied one by one from the uppermost layer with a paper feed roller, a pickup roller and the like provided in the vicinity of the paper feed cassette.
Conventionally, in a paper feed cassette, a lift plate is provided in which sheets are placed on its upper surface and which raises and lowers a sheet stack. In the lift plate, an upstream end in the feed direction is supported to the inner side of the bottom surface of the paper feed cassette. The lift plate can be turned about the supporting point of the upstream end in the feed direction with an end portion on the downstream side in the feed direction serving as a turning end. In the paper feed cassette, a lift mechanism is also provided which raises and lowers the turning end of the lift plate. A drive force is transmitted to the lift mechanism through a main body gear provided in the main body of the image forming apparatus, an input gear provided in the cassette side surface portion of the paper feed cassette and the like.
Incidentally, the lift plate affects the accuracy of paper feed, and thus the accuracy of the position is required. However, in the conventional image forming apparatus, the lift plate is provided in the paper feed cassette. Hence, both the accuracy of the position of the lift plate with respect to the sheet storage portion of the paper feed cassette and the accuracy of the position of the sheet storage portion with respect to the main body of the image forming apparatus are required.
In the lift plate, the sheet stack is raised and lowered, and thus rigidity is required. In the conventional image forming apparatus, the lift plate is provided in the paper feed cassette, and thus for the paper feed cassette which supports the lift plate, rigidity is also required. Hence, the weight of the paper feed cassette is increased, and thus the operability thereof by a user is lowered.